PCI: dwc: Add accessors for write permission of DBI read-only registers

The read-only DBI registers can be written only when the "Write to RO
Registers Using DBI" (DBI_RO_WR_EN) field of MISC_CONTROL_1_OFF is set.

Add accessors to enable and disable write permission, and use them instead
of accessing MISC_CONTROL_1_OFF directly.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Joao Pinto <jpinto@synopsys.com>
Acked-by: Roy Zang <tie-fei.zang@freescale.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
index 7366c8167404..0c5f874345f6 100644
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -76,6 +76,9 @@
 #define PCIE_ATU_FUNC(x)		(((x) & 0x7) << 16)
 #define PCIE_ATU_UPPER_TARGET		0x91C
 
+#define PCIE_MISC_CONTROL_1_OFF		0x8BC
+#define PCIE_DBI_RO_WR_EN		(0x1 << 0)
+
 /*
  * iATU Unroll-specific register definitions
  * From 4.80 core version the address translation will be made by unroll
@@ -279,6 +282,28 @@ static inline u32 dw_pcie_readl_dbi2(struct dw_pcie *pci, u32 reg)
 	return __dw_pcie_read_dbi(pci, pci->dbi_base2, reg, 0x4);
 }
 
+static inline void dw_pcie_dbi_ro_wr_en(struct dw_pcie *pci)
+{
+	u32 reg;
+	u32 val;
+
+	reg = PCIE_MISC_CONTROL_1_OFF;
+	val = dw_pcie_readl_dbi(pci, reg);
+	val |= PCIE_DBI_RO_WR_EN;
+	dw_pcie_writel_dbi(pci, reg, val);
+}
+
+static inline void dw_pcie_dbi_ro_wr_dis(struct dw_pcie *pci)
+{
+	u32 reg;
+	u32 val;
+
+	reg = PCIE_MISC_CONTROL_1_OFF;
+	val = dw_pcie_readl_dbi(pci, reg);
+	val &= ~PCIE_DBI_RO_WR_EN;
+	dw_pcie_writel_dbi(pci, reg, val);
+}
+
 #ifdef CONFIG_PCIE_DW_HOST
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp);
 void dw_pcie_msi_init(struct pcie_port *pp);